Common rail injector

Abstract

The invention relates to a common rail injector for injecting fuel in a common rail injection system of an internal combustion engine, having an injector housing which communicates with a central high-pressure reservoir and in which a nozzle needle that cooperates with a valve piston which is guided in a valve piece is axially displaceable. To increase the service life of the injector, the end toward the nozzle needle of the valve piston or of a thrust rod triggered by the valve piston is guided coaxially to the axis of symmetry of the nozzle needle.

We claim:  
     
       1. The fuel injector for injecting fuel in an internal combustion engine, said injector having an injector housing ( 1 ) which communicates with a central high-pressure reservoir and a nozzle needle ( 14 ) that cooperates with a valve piston ( 6 ) which is axially displaceable and guided in a valve piece ( 2 ), the improvement wherein the end of the nozzle needle ( 14 ) toward the valve piston ( 6 ) protrudes into a guide sleeve ( 16 ), and the end of the valve piston ( 6 ), or an end of a thrust rod ( 8 ) triggered by the valve piston ( 6 ), oriented toward the nozzle needle ( 14 ) is also received in the guide sleeve ( 16 ), further comprising a cylindrical recess ( 22 ) formed on said guide sleeve ( 16 ), on its face end toward the nozzle needle ( 14 ), and wherein, on the end of the nozzle needle ( 14 ) toward the valve piston ( 6 ), a thrust peg ( 15 ) is positioned, said thrust peg protruding into the guide sleeve ( 16 ) or into a central blind bore formed on the end of the valve piston ( 6 ). 
     
     
       2. The fuel injector according to  claim 1 , wherein the valve piston ( 6 ) or thrust rod ( 8 ) and the guide sleeve ( 16 ) form a unit, and wherein a blind bore is formed centrally in an end of the unit toward the nozzle needle, the end of the nozzle needle ( 14 ) toward the valve piston being received in said blind bore. 
     
     
       3. The fuel injector according to  claim 2 , wherein on the end of the nozzle needle ( 14 ) toward the valve piston ( 6 ), a thrust peg ( 15 ) is embodied, said thrust peg protruding into the guide sleeve ( 16 ) or into a central blind bore formed on the end of the valve piston ( 6 ). 
     
     
       4. The fuel injector according to  claim 2 , further comprising a thrust rod ( 8 ) cooperating axially with said valve piston ( 6 ), said thrust rod ( 8 ) being disposed so as to be slightly pivotable relative to the longitudinal axis of the valve piston ( 6 ). 
     
     
       5. The fuel injector according to  claim 1 , further comprising a bearing disk on the face end of the guide sleeve ( 16 ) remote from the nozzle needle ( 14 ) between the guide sleeve ( 16 ) and a nozzle spring ( 18 ), said bearing disk forming an abutment for the nozzle spring ( 18 ). 
     
     
       6. The fuel injector according to  claim 5 , further comprising a cylindrical recess ( 22 ) formed on said guide sleeve ( 16 ), on its face end toward the nozzle needle ( 14 ). 
     
     
       7. The fuel injector according to  claim 5 , further comprising an adjusting piece ( 19 ) disposed between the nozzle needle ( 14 ) and either the valve piston ( 6 ) or the thrust rod ( 8 ). 
     
     
       8. The fuel injector according to  claim 1 , further comprising a collar on the guide sleeve ( 16 ), on its face end remote from the nozzle needle ( 14 ), said collar ( 28 ) forming an abutment for the nozzle spring ( 18 ). 
     
     
       9. The fuel injector according to  claim 8 , further comprising a cylindrical recess ( 22 ) formed on said guide sleeve ( 16 ), on its face end toward the nozzle needle ( 14 ). 
     
     
       10. The fuel injector according to  claim 1 , wherein the dimensions of the guide sleeve ( 16 ), on its face end remote from the nozzle needle ( 14 ), are adapted to the dimensions of the nozzle spring ( 18 ). 
     
     
       11. The fuel injector according to  claim 10 , further comprising a thrust rod ( 8 ) cooperating axially with said valve piston ( 6 ), said thrust rod ( 8 ) being disposed so as to be slightly pivotable relative to the longitudinal axis of the valve piston ( 6 ). 
     
     
       12. The fuel injector according to  claim 1 , further comprising an adjusting piece ( 19 ) disposed between the nozzle needle ( 14 ) and either the valve piston ( 6 ) or the thrust rod ( 8 ). 
     
     
       13. The fuel injector according to  claim 1 , further comprising a bearing disk on the face end of the guide sleeve ( 16 ) remote from the nozzle needle ( 14 ) between the guide sleeve ( 16 ) and a nozzle spring ( 18 ), said bearing disk forming an abutment for the nozzle spring ( 18 ). 
     
     
       14. The fuel injector according to  claim 1 , further comprising on the guide sleeve ( 16 ), on its face end remote from the nozzle needle ( 14 ), said collar ( 28 ) forming an abutment for the nozzle spring ( 18 ). 
     
     
       15. The fuel injector according to  claim 1 , wherein the dimensions of the guide sleeve ( 16 ), on its face end remote from the nozzle needle ( 14 ), are adapted to the dimensions of the nozzle spring ( 18 ). 
     
     
       16. The fuel injector according to  claim 1 , further comprising a cylindrical recess ( 22 ) formed on said guide sleeve ( 16 ), on its face end toward the nozzle needle ( 14 ). 
     
     
       17. The fuel injector according to  claim 1 , further comprising an adjusting piece ( 19 ) disposed between the nozzle needle ( 14 ) and either the valve piston ( 6 ) or the thrust rod ( 8 ). 
     
     
       18. In a fuel injector for injecting fuel in an internal combustion engine, said injector having an injector housing ( 1 ) which communicates with a central high-pressure reservoir and a nozzle needle ( 14 ) that cooperates with a valve piston ( 6 ) which is axially displaceable and guided in a valve piece ( 2 ), the improvement wherein the end of the nozzle needle ( 14 ) toward the valve piston ( 6 ) protrudes into a guide sleeve ( 16 ), and the end of the valve piston ( 6 ) or an end of a thrust rod ( 8 ) triggered by the valve piston ( 6 ), oriented toward the nozzle needle ( 14 ) is also received in the guide sleeve ( 16 ), further comprising a thrust rod ( 8 ) being disposed so as to be slightly pivotable relative to the longitudinal axis of the valve piston ( 6 ). 
     
     
       19. The fuel injector according to  claim 18 , further comprising a blind bore ( 7 ), in the end of the valve piston ( 6 ) toward the nozzle needle ( 14 ), said blind bore ( 7 ) receiving a tapering end of the thrust rod ( 8 ). 
     
     
       20. In a fuel injector for injecting fuel in an internal combustion engine, said injector having an injector housing ( 1 ) which communicates with a central high-pressure reservoir and a nozzle needle ( 14 ) that cooperates with a valve piston ( 6 ) which is axially displaceable and guided in a valve piece ( 2 ), the improvement wherein the end of the nozzle needle ( 14 ) toward the valve piston ( 6 ) protrudes into a guide sleeve ( 16 ), and the end of the valve piston ( 6 ) or an end of a thrust rod ( 8 ) triggered by the valve piston ( 6 ), oriented toward the nozzle needle ( 14 ) is also received in the guide sleeve ( 16 ), wherein the end of the valve piston ( 6 ) toward the nozzle needle ( 14 ) can be deflected elastically in the radial direction out of the axis of symmetry of the valve piston ( 6 ). 
     
     
       21. The fuel injector according to  claim 20 , further comprising a cylindrical recess ( 22 ) formed on said guide sleeve ( 16 ), on its face end toward the nozzle needle ( 14 ). 
     
     
       22. The fuel injector according to  claim 20 , further comprising a bearing disk on the face end of the guide sleeve ( 16 ) remote from the nozzle needle ( 14 ) between the guide sleeve ( 16 ) and a nozzle spring ( 18 ), said bearing disk forming an abutment for the nozzle spring ( 18 ). 
     
     
       23. The fuel injector according to  claim 20 , further comprising a collar on the guide sleeve ( 16 ), on its face end remote from the nozzle needle ( 14 ), said collar ( 28 ) forming an abutment for the nozzle spring ( 18 ). 
     
     
       24. The fuel injector according to  claim 20 , wherein the dimensions of the guide sleeve ( 16 ), on its face end remote from the nozzle needle ( 14 ), are adapted to the dimensions of the nozzle spring ( 18 ). 
     
     
       25. The fuel injector according to  claim 20 , further comprising an adjusting piece ( 19 ) disposed between the nozzle needle ( 14 ) and either the valve piston ( 6 ) or the thrust rod ( 8 ). 
     
     
       26. The fuel injector according to  claim 20 , wherein a thrust rod ( 8 ) is provided, which cooperates axially with said valve piston ( 6 ), said thrust rod ( 8 ) being disposed so as to be slightly pivotable relative to the longitudinal axis of the valve piston ( 6 ). 
     
     
       27. The fuel injector according to  claim 20 , further comprising a blind bore ( 7 ), in the end of the valve piston ( 6 ) toward the nozzle needle ( 14 ), said blind bore ( 7 ) receiving a tapering end of the thrust rod ( 8 ). 
     
     
       28. The fuel injector according to  claim 20 , wherein the end of the valve piston ( 6 ) toward the nozzle needle ( 14 ) can be deflected elastically in the radial direction out of the axis of symmetry of the valve piston ( 6 ).